I. Field
The present invention relates to data communication. More particularly, the present invention relates to a novel and improved method and apparatus for maintaining an Internet Protocol (IP) session with a radio network while not tuned to the radio network.
II. Background
The explosive growth of computer networks, such as the Internet, has spawned demands for high data rate infrastructures that can support the enormous amount of data traffic generated by these networks. Approximately concurrent with the growth of the Internet is the deployment and acceptance of wireless communication systems capable of supporting a variety of applications. However, earlier generations of wireless communication systems are generally designed for voice communication and may not be as efficient at transmitting data traffic generated by the Internet.
An example of such earlier generation wireless communication systems is a code division multiple access (CDMA) system disclosed in U.S. Pat. No. 4,901,307, entitled “SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS,” issued Feb. 13, 1990, and U.S. Pat. No. 5,103,459, entitled “SYSTEM AND METHOD FOR GENERATING SIGNAL WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM,” issued Apr. 7, 1992. A newer generation CDMA communication system designed to efficiently transmit packet data is disclosed in U.S. Pat. No. 6,574,211, entitled “METHOD AND APPARATUS FOR HIGH RATE PACKET DATA TRANSMISSION,” issued Jun. 3, 2003 (hereinafter, the HDR system). These patents and patent application are assigned to the assignee of the present invention and incorporated herein by reference.
CDMA systems are typically designed to conform to one or more CDMA standards. Examples of such CDMA standards include: (1) the “TIA/EIA/IS-95-B Mobile Station-Base Station Compatibility Standard for Wideband Spread Spectrum Cellular Systems” (hereinafter, the IS-95 standard); (2) the TIA/EIA/IS-98-A, -B, -C, and -D standards entitled “Recommended Minimum Performance Standard for Dual-Mode Spread Spectrum Cellular and PCS Mobile Stations” (hereinafter, the IS-98 standard); (3) the standard offered by a consortium named “3rd Generation Partnership Project 2” (3GPP2) and embodied in a set of documents including Document Nos. C.S0002-A, C.S0005-A, C.S0010-A, C.S0011-A. C.S0024, and C.S0026 (hereinafter, the cdma2000 standard); and (4) the standard offered by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (hereinafter, the W-CDMA standard). The HDR system can be designed to conform to the specifications defined in a document entitled “TIE/EIA/IS-856 cdma2000 High Rate Packet Data Air Interface Specification,” (hereinafter, the HDR Specification). The standards are incorporated herein by reference.
Given the ever-growing demands for wireless data communication for a variety of applications, multiple radio networks may be concurrently deployed to cover a particular geographic area. In such overlay deployments, one radio network (e.g., a cdma2000 CDMA radio network) may be deployed to provide voice, data, paging, and other services, and another radio network (e.g., an HDR radio network) may be deployed to provide packet data services. These radio networks may interact via a network interface, such as the one defined by the “Inter-operability Specification (IOS) for cdma2000 Access Network Interfaces” (hereinafter, the Inter-operability Specification), which is incorporated herein by reference.
A multi-mode access terminal can be designed with the capability to communicate with multiple radio networks for various types of services. For such designs, the access terminal may initiate an Internet Protocol (IP) session with the HDR radio network for data services and may thereafter initiate another session with a CDMA radio network (e.g., one that conforms to cdma2000, W-CDMA, or some other standard) to receive voice, paging, or other services. For enhanced services, it is desirable for the access terminal to be able to maintain IP connectivity even if it moves between the HDR and CDMA radio networks.
Thus, techniques to efficiently maintain IP connectivity in overlay deployments of multiple (e.g., HDR and cdma2000) radio networks are highly desirable. It is also desirable that such techniques can be implemented with minimal or no changes to existing specifications and operation of the CDMA radio network.